A barrier installed in a curbside drain opening which detains solid trash at no or slow rate flow rates, but which opens when the rate is sufficiently high, is shown in Martinez U.S. Pat. No. 6,217,756. The objective of this patent, and of the instant invention, is to impede the entrance of solid trash into the drain from a gutter while permitting slow water flow, and to open up when the flow is heavy so as to pass it.
Of course, when a heavy flow of water arrives and the barrier opens, whatever solid trash is already detained at the opening, or is up the gutter, will be washed into the drain. However, when there is no flow, or only slow flow, the detained trash can readily be swept away by a street sweeper. In effect, this barrier keeps out of the downstream drain system trash which accumulates during dry periods if the street is properly swept.
Municipalities are well aware of the costs when trash enters a drainage system. Generally there is a catch basin into which water and trash that passed through the drain opening are deposited. This trash must be removed, usually on a periodic basis. A heavy cover is removed, and then depending on what is in there, a man must go into the basin properly equipped to clear it out. If for some reason the basin is not properly cleaned out, and a rapid flow of water arrives, the drain can be plugged, and a flood ensues. Proper maintenance is necessary.
Of even greater concern is what arrives downstream from the basin. Sooner or later, all material that is not removed near the source will reach a water system. In some states this is a river or lake. In others it is an ocean or a bay. In every such situation, there result troublesome accumulations of trash and often pollution. These events often occur at places where it is difficult to retrieve the trash, and sometimes it is too late, especially when soluble or small particles are involved and they are dispersed into the environment.
To counter the risk, and depending on the scope of the drainage system, catch dams are often provided downstream which must periodically be cleaned out at great expense. It is best practice to exclude trash from them to the maximum extent possible while they are dry, and while the trash is readily accumulated in condition for easier collection at the curbside.
Still, means for this purpose should not interfere with the primary objective of the drainage system, which is to protect the surrounding area against flooding when the flow is heavy, such as in hard rainstorms or thunderstorms. In those events, the system must be maximally open and cannot be permitted to plug up. Apparatus according to this invention helps to assure system open-ness, because it can prevent most of the trash from entering the system in the first place.
An inherent problem with known devices such as in the aforementioned Martinez patent is that, while they need to remain open during times of heavy flow, they should close when the flow slows, but still stay open in case the system has already opened and then backs up and floods the catch basin. The said patented device can lose its control function when the system backs up, and the barrier can close, which can result in a flooded condition.
It is an object of this invention to provide a barrier that is normally closed during no or slow water flow rates, is reliably open when the rates increase, and reliably closes when the water in the basin recedes.
Optionally, means can be provided to keep the barrier open whenever the water level in the basin rises above some reference level and there may be no adequate flow past the control to keep the barrier open. With this improvement the system's control devices cannot be overwhelmed by being immersed in standing water in a flooded basin.